Prevention of degradation of textile fibers by acids



mama Jan. 3, 1950 um'rso sra'rs ras-vnn'rron or DEGRADATION F 'rsxms mans or ACIDS retary of Agriculture No Drawing. Application March 29, 1946,

' Serial No. 658,202

(Cl. 206-84) (Granted under the act of March 3, 1883, as

1 Claim.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

' The object of the present invention is to disclose a method of preventing the acid-degradation of textile fibers, particularly industrial cords, threads, and fabrics exposed to acid vapors, and a new type of acid-resistant textile structure.

It is well known that industrial fabrics that are exposed to acid vapors rapidly deteriorate, whereby their service life is greatly, shortened. a particular example of such acid-degradation is that of the weakening of the sewing thread used to sew multi-wa1l paper'bags for the shipment of the fertilizer, triple superphosphate. In this case, the fertilizer contains not only the acid constituent, CaH4(PO4) 2, but also some free phosphoric acid and a small amount of chlorides and fluorides as impurities. The thread is subjected to some acid action of halogen acids due to gradual freeing of these halogen acids. This is especially true of "green or new fertilizer which has not had time to lose most of the halogen acids. When such fertilizer is packed in multiwall paper bags, which are almost airtight except at the top, the breathing. action of the bag, due to atmospheric changes or to moving of the bag, probably causes the sewing thread at the top of the bag to be subjected to these vamm. It is well known that such vapors, after dissolving in the natural moisture of the thread, exert a degradative, hydrolytic' action which is probably catalytic in that its action is continuous over a long period of time. Such degradative action is also exerted on the cotton of the cloth bags which may also be used to ship such fertilizer. It is one of the objects of the present invention to disclose a treatment which will prevent, or mitigate such degradative action.

There have been numerous attempts on the part of various investigators to prevent acid degradation of textilematerials. such as cotton thread or cloth. The use of sodium carbonate on cloth bags for holding superphosphate or other fertilizers has been patented by L. J. Pettett, J. R. Brown, and H. N. Mills in U. S. Patent 2,036,357. Such treatment with alkaline agents is suflicient, if the cloth is to be subjected to only a small amount of acid. After neutralization, however, the cloth is once again left unprotected. C. deGuide (British Patent 19,473 (1910)) has patamended April 30, 1928; 370 0. G. 757) ented the use of soap solution to extend the life of cloth sacks for shipping fertilizer. The use of sodium silicate with sodium stearate has been patented by Cotton, et al. (British Patent 345,468,

March s, 1930).

in the fertilizer, the strength is reduced to 1 to 1.5 pounds. If, however, the thread be treated with about percent of the humectant agents 20 named below, the following results are obtained:

Dietbanolamine.

1 l imtmcnt Pounds Passes:- "route-"nu Trieth anolaminc We believe that this protective action is at least partially due to the fact that the acids are distributed through a relatively large amount of solvent, rather than the comparatively smail amount of water naturally present in the thread.

Also, ionization in these new media may be less extensive, so that the pH is correspondingly higher. In addition, the buffering action of such a humectant agent as triethanolamine is undoubtedly helpful, because it will stabilize the pH with its high alkaline reserve. The humectant action is particularly illustrated by glycerol and sorbitol, where .there is no possibility of neutralization. We have found that the humectant agent must be thoroughly distributed throughout the thread, or degradation will result at points in the thread which are unprotected. These theories as to the nature of the action of the materials are not intended to restrict the claims of this invention, but are of interest as indicating factors which we believe are active in the mechanism of this novel type of protection.

That the action of these agents is not limited tocotton is shown in the table at the end of these specifications. This table presents the results of tests in which a variety of textile materials in threads of various construction were stored in miniature bags of fertilizer for 24 hours at 60 C.

Table.-Bag tests on cord '4 EXAMPLEIIIN If the thread of Example I is wet with a dilute solution of a wetting or penetrating agent, or extracted with alcohol prior to impregnation, the latter may be carried out at room temperature.

In this case, the thread strength loss is 30.9 per cent or 29.1 percent, respectively.

It is apparent from the above examples that temperature, diluent, and other conditions may be varied without affecting the essential features of the invention.

and threads from various fibers Siren th Pei-mg. Riagent g so Alter Treatment Fiber Used g g ggf Control Glycerol Triethanolamine L Glycerol TEA 1 Percent of Percent of Percent of original original Original 4 22.9 11.0 1.8 16.4 9.7 88.2 26. 3 26. 4 114 46 40. 4 59 51. 8 97 85. 1 27. 7 30. 0 94 21 22. 3 54 57. 4 83 88. 3 25. 8 26. 2 67 6 9. 0 32 47. 7 72 107. 18. 5 21. 4 l9. 8 8. 8 44. 0 13. 2 66. 6 18. 6 94 Paper Cord Z8- 0 23- 9 7. 8 1. 2 15. 4 2. 6 33. 6 4. 7 60. 2 Viscose Rayon 26- 0 1 12. 2 4- 5 37. 5 5. 4 44. 3 9. 0 73. 8

1 TEATriethan01amine. I Specially prepared laboratory sample.

EXAMPLEI -A solution of triethanolamine is made up, consisting of grams of triethanolamine and grams of water. If this be heated approximately to the boiling point (about 101 C.) it is impregnated readily into sewing thread. The thread is then put through squeegee rolls to reduce the solution content to such a point as to leave, when dried, about 20 grams of triethanolamine for every grams of cotton. The thread containing this amount of agent feels soft and dry enough to be used for sewing. The amount of reagent left in may be varied according to the use to I which it is to be put and t0 the necessary characteristics needed for sewing with the particular machine to be used. The thread may also be waxed, if this be desired, as an aid to sewing. Thread-strength loss was 11.8 percent with this treatment, when the thread was buried. in 3 pounds of green fertilizer for 24 hours at 60 C., as compared to a loss of 83.6 percent for untreated thread.

EXAMPLE II REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 153,477 Croasdale July 28, 1874 211,206 Ende Jan. 7, 1879 2,067,175 Dickie et al. Jan. 12, 1937 2,067,202 Pool et al Jan. 12, 1937 2,201,041 Katz May 14, 1940 2,332,020 Simpson Oct. 19, 1943 2335.701 Vallandigham Feb. 10, 1948- FOREIGN PATENTS Number Country Date 271 Germany 1877 OTHER REFERENCES Synthetic Organic Chemicals, Carbide, and 

